Mass Effect 3 is an action role-playing video game and the third installment of the Mass Effect video game series, developed by BioWare and published by Electronic Arts (EA), the first in the series to not be published by Microsoft Game Studios (MGS). Upon its release on March 6, 2012, for the PlayStation 3, Xbox 360, and Windows, Mass Effect 3 generated controversy when its ending was poorly received by players who felt that it did not meet their expectations. Criticisms included the ending rendering character choices inconsequential, a general lack of closure, plot holes, and narrative inconsistency.

On June 26, 2012, developers released an Extended Cut as downloadable content (DLC) intended to clarify the endings and remedy fan concerns. The initial announcement of the development of add-on content to amend the ending as well as the subsequent release of Extended Cut sparked debates over the treatment of video games as art and whether BioWare should have to alter their vision of the work in response to external pressure, regardless of its quality.

Background In the original Mass Effect trilogy, Commander Shepard, the customizable player character, leads allies from across the Milky Way galaxy in a struggle against a collective of powerful synthetic lifeforms called the Reapers, who systematically annihilate all sentient spacefaring life every 50,000 years. By the events of Mass Effect 3, the Reapers have arrived in the galaxy, and begin harvesting entire worlds. To stop them, Shepard must form an alliance between all of Mass Effects alien races to build the Crucible, a megastructure-sized device capable of stopping the Reapers. It is built from blueprints designed by the civilizations from previous cycles, including the Protheans who successfully delayed the onset of the current cycle at the cost of their own near-extinction.

As Shepard, players dispatch a final "Marauder" enemy, entering a Reaper teleportation beam on Earth to reach the Citadel alongside their close ally and mentor, David Anderson, and begin the game's ending sequence. This follows a long and grueling battle in London where Shepard is gravely wounded by Harbinger, the leader of the Reapers. Once there, Shepard and Anderson engage in a dialog-based final showdown with the Illusive Man, the leader of Cerberus; only Shepard survives the confrontation. Shepard then attempts to fire the Crucible, only to be transported to the Citadel's pinnacle. They encounter the Catalyst, or "Star Child," the holographic avatar of the Reaper gestalt intelligence in the form of a boy Shepard had failed to rescue earlier in the game. The Catalyst reveals the Reapers' true motives, explaining that this repeated culling is intended as a form of preservation due to the supposed inevitability of organic life being rendered extinct by their own synthetic creations.

The Catalyst then presents up to three options for activating the Crucible, which will break the Reapers' galactic cycle of extinction: Destroy the Reapers at the cost of annihilating all synthetic life as collateral damage, including allies such as EDI and the Geth. Control the Reapers, with the caveat that Shepard will die and "lose everything they have" when their mind is uploaded to become the new Catalyst. Merge all organic and synthetic life via synthesis, resulting in both life forms achieving a "perfect understanding."

By making any of the above choices, Shepard activates the Crucible, which emits a wave of energy that spreads throughout the galaxy via the mass relays, destroying the mass relay network in the process. As the Normandy is hit by the wave of energy, it crashes on a remote planet.

Development Chris Hepler, one of the game's writers and the project's de facto "loremaster", explained in a 2021 interview that the final ending decision was both easier and had "much more project momentum", and that it was embraced by the project leads almost immediately, including its use of "space magic". The controversial aspects about the endings, such as Destroy ignoring the AI problem the Reapers aimed to prevent, Control rewarding the Reapers, and Synthesis violating the galaxy's bodily autonomy, were intentional in order to not make any of the choices perfectly moral or "right" for everyone. However, he also agreed that the game hinted at alternate endings that could have been used, and that a more hard science-based ending had been considered.

Concept scenarios for alternate endings that were discarded included the following:

Dark energy The developers attempted to write a viable ending around the concept of dark energy and had considered a number of hypothetical theories surrounding it as the reason behind the creation of the Reapers: examples that were proposed by team members included curbing the use of dark energy by organic civilizations due to its cumulative entropic effect that would hasten the end of the universe, or preventing the universe's inevitable descent into a Big Crunch by focusing on organic species with biotic potential. The game was acknowledged to contain direct hints that the Citadel species and the Reapers would team up to stop a dark energy anomaly that threatened the universe with destruction, although this was not seriously discussed by the writers.

Cyclical ending This ending scenario, shared by series concept artist Matt Rhodes on his personal website, envisions a villainous Shepard being confronted by either Ashley Williams or Kaidan Alenko, the survivor of the Virmire incident from the first game, after being willingly modified by Reaper technology. This is intended to echo the character arc and downfall of Saren Arterius in the first Mass Effect as a "cyclical twist".

Illusive Man boss fight An endgame scenario which never progressed past the concept art stage would have the Illusive Man transform into a Reaper creature, not unlike Saren at the end of the first game, for a final boss fight.

Detonating mass relays as a trap for the Reapers Former Mass Effect lead writer Drew Karpyshyn revealed in a July 2022 interview that a proposed ending which was under serious consideration by the team would involve the Reapers being lured through the mass relays, and the entire network is then detonated to wipe them out. Since every galactic community is isolated from each other as a result of the damaged relays, it would serve as the premise for a direct sequel which would have been the fourth main series installment.

Strong nuclear force ending Hepler's preferred ending eschewed "space magic" entirely and involved the Crucible being a weapon that annihilated objects with a high atomic number, including the Reapers, their creations, such as the Husks (which were implied to be created with niobium cybernetics) and Commander Shepard themselves, an idea inspired by Probability Moon by Nancy Kress. However, the final ending was approved too quickly for Hepler to pitch his idea, and he was afraid of being sued for copying the idea without permission.

Reaper Queen Shepard would discover a Reaper "Queen" that had been trapped somewhere within the Citadel and would then be prompted with three choices on how to deal with her. The choices offered by this discarded scenario ended up being similar in nature to the choices offered by the Catalyst in the final game's ending.

Response Although Mass Effect 3 launched in early March 2012 to a predominantly positive critical reception, its endings received a very poor reception from players. By mid-March 2012, a contingent of displeased fans had organized an internet campaign called "Retake Mass Effect" to demand a better ending to the game, part of which included a charity drive for the organization Child's Play. The drive raised $80,000 in less than two weeks before it was stopped. One fan made a complaint to the Federal Trade Commission, arguing that BioWare did not deliver on the promise of its game. Marjorie Stephens, Better Business Bureau director of marketplace services, alleged that the game falsely advertised the ability to completely shape the outcome. However, in June 2012, the UK Advertising Standards Authority ruled that, while disappointing, the endings were different enough to not be misleading to an actionable extent.

Opinions over the game's endings divided many critics. Among the criticisms include the ending rendering character choices inconsequential; a general lack of closure; lore contradictions and plot holes; character and narrative inconsistencies; the absence of a final boss battle; and inconsistencies between statements by BioWare staff during the game's development and the form the endings ultimately took. Commentators took note of the magnitude and scale of the public reaction and highlighted how invested the series had made its players. A widely discussed fan theory proposed that the endings were a hallucinated consequence of Shepard's gradual, forcible Reaper indoctrination over the course of the trilogy, also positing that the "Destroy" ending was purposely colored red to dissuade Shepard from picking it, and thus, overcoming the mind control. Dissatisfied fans also turned the final enemy unit encountered in combat into a sarcastic Internet meme called Marauder Shields.

A number of individuals associated with Mass Effect 3, such as project director Casey Hudson and cast member Jessica Chobot, initially spoke out in support of the ending shortly after the game's launch. By March 16, 2012, Hudson and community coordinator Chris Priestly had acknowledged the growing controversy and provided assurances that the team were listening to feedback. Hudson later went on record and conceded that players ought to have more closure and answers for the creative direction they had taken. BioWare co-founder Ray Muzyka later announced that the company planned to address the criticism, with a further announcement to be made in April 2012. Chobot issued a public apology on a blog post dated April 2, 2012 following backlash from some players in response to her choice of tone and words.

BioWare announced a free downloadable content pack on April 5, 2012, that would expand upon the ending. Some commentators expressed concerns that changing the endings by giving into fan demand would compromise the developers' creative vision as well as the artistic integrity of their work, and ultimately sets a bad precedent for the development of creative works in the video game industry. Video game developer Ken Levine remarked that he felt sad that players were fervently calling for a revised Mass Effect 3 ending as they would be left “disappointed”. Others like Stephen Totilo from Kotaku welcomed BioWare's decision to be open towards revising the ending to their work.